Sing Me A Lullaby
by hullosweetpea
Summary: They needed a plan. Something to prevent additional harm. Natasha has a plan, but Bruce needed to agree. It didn't take long though for him to be wrapped up in her spider's web once she wove his lullaby.
1. Chapter 1

**A/N: BEWARNED! SPOILERS FOR AGE OF ULTRON BE AHEAD! I don't mind Bruce/Natasha and in fact I find it a bit refreshing, but I wish there was a better build up. More of a reason; I mean, after the movie I see potential, but it's the premovie stuff that they don't show that I want to know about. For me, this is the beginning. It's set after The Avengers, but before CAWS, as Natasha is still here,**

Sing Me a Lullaby

Natasha descended the steps down to the lab where Bruce was deep in his work. "Bruce," she said softly.

"Hmm," he looked up and smiled when he saw Natasha.

"I have an idea."

He pulled his glasses off and rolled away from the lab table. "For what."

"For when, you know, the other guy comes out."

"Natasha, it's a nice offer, but I can't let you-"

"Banner, we both know that if you can't contain the Hulk civilians can be harmed."

He sighed. "I have everything under control, Romanoff. I do yoga. I'm relaxed."

"That's not what I mean. I mean afterwards, when we've already won and we need you back. We need a plan of action."

"Natasha."

She crossed her arms. "I'm sorry, but their Fury's orders."

Bruce leaned back in his chair and crossed his arms. "But why are you the one doing this."

She shrugged her shoulders. "I almost had you in the helicarrier; you almost came back. I want to try something and I think it might work."

Bruce rolled back over to his lab table. "Thanks, but no thanks. I'm not hulking out here and putting potential citizens in harm's way."

She shook her head. "I'm not talking about bringing out the other guy. At least not yet. I want to practice with you. If you recognize it as Banner I think it will work to bring you out of the big guy."

Bruce sighed and pushed his chair back out and gestured to the one beside him. "Five minutes. And then we don't talk about it for a while."

Natasha nodded and sat down. "If that's what you want Banner." She evened her breathing and looked Banner in the eye, staring into his soul. "To start, we need a key phrase. Something that will prepare you for what will come next. Reminding you of what's happening."

He blinked. "Do you have anything in mind?"

"The sun is setting soon."

Bruce rubbed the back of his neck. "I don't know Romanoff-"

"That's not all of it. It's just the trigger."

"Then what's the other part?"

She held up her hand facing him. "Now hold yours up to mine."

He looked hesitantly at her before letting his palm just ghost over hers.

She breathed in and slowly pushed her hand forward, touching his hand. She lifted it back before carefully running her hand down his forearm; her fingers gently caressing his arm. She felt Bruce tense up under fingers. "Relax, Banner." He let go of his held breath as her fingers trailed back over his hand, just barely latching on as her fingertips pulled up. "What do you think? Will it work?"

Bruce ran his hand over his face. "I don't know. It might, it might not. The only way to test it is if I let the other guy have control and I really don't want to do that."

She sighed. "Then let's try it again." She looked him in the eyes. "Hey, the sun is setting soon." She continued to stare into his eyes as she went through the motions, never losing contact. As her fingers danced down his arm she faintly felt his pulse elevate.

Bruce started to even his breathing to keep his cool. When Natasha finished she didn't break eye contact until Bruce cleared his throat. "Um, uh, I think that's enough for one day, don't you?"

She nodded. "Of course we can work on this some other time." She left the lab and walked up the stairs. She entered the elevator to go back to the main floor and met Steve inside. "How did it go? Did it work?"

Natasha sighed. "I don't know. I really won't know until the big guy's here."

Steve patted her shoulder. "You're taking baby steps and that's fine. It won't work if Bruce is resisting you."

"You're right, but...JARVIS?"

 _Yes, Miss Romanoff?_

"Take me back down to the lab and whatever you do don't let the others interfere, especially Tony."

 _As you wish_

The elevator began to descend.

"Nat, what are you doing," asked Steve cautiously.

She pulled a gun from her holster and checked the clip. "I'm not taking baby steps, Rogers." The elevator doors opened and she stepped out.

"Romanoff, come back here!"

She switched the safety off. "JARVIS, please detain Rogers in the elevator until further notice."

 _Certainly, Miss Romanoff_

The elevator doors closed leaving Steve inside banging on the door.

She flipped her hair out of the way and started to sneak forward.

"Tony," she heard Bruce shout, "is that you?"

She aimed and fired, letting the bullet just barely graze Bruce's arm. His hand went up to the wound in shock. She watched as his eyes flashed green and she heard muscle, skin and bones crunch as they grew in size. She was mesmerized as Bruce turned into the massive Hulk. With a scream he began to throw objects out of his way as he rampaged across the lab, looking for the shooter.

Natasha put her gun away and slowly stepped out from her hiding spot, hands up. "Hey!"

Hulk looked over and frowned at her.

She took a deep breath. "The sun's setting soon."

Hulk growled and slapped her out of the way and into the glass wall, causing it to shatter.

"Natasha," shouted Steve from inside the elevator. "JARVIS, let me out!"

She sat up and pointed at the elevator. "Don't you dare! JARVIS, Keep him in there." She flipped forward and landed in front of the Hulk. He tried to punch her, but she rolled and dodged. He reached out and grabbed her by the leg; roughly throwing her up in the air.

She grabbed hold to an exposed pipe before dropping back down when his back was turned. He heard the soft thud she made as she connected with the floor and he reached out and grabbed her by the waist. He pulled her relatively closed to his face and screamed. Her breathing was labored. "The sun is setting soon."

Hulk frowned at her again and started to throw her down, but she stuck her hand out. Hulk cocked his head to the side and slowly raised his hand up to hers.

Natasha blinked rapidly as she saw her small pale hand against his gigantic green one. She slowed her breathing, never breaking eye contact, as she pulled her arm away and began to trace her fingers across his veins.

Hulk watched her delicate fingers as they moved down his arm, briefly stopping at his wrist. She continued until she held on by only her fingertips, letting them linger before slowly slipping them away.

The Hulk dropped her to the floor and began to stagger backward, confused. Natasha watched as he fell to the lab floor and he began to shrink back into Bruce. She sat up from the rubble and walked over to him. He sat up with dazed eyes looking around. "Natasha." He looked at her cuts and scrapes, the blood in her hair.

"Natasha, are you all right? Did I hurt you?"

"I'm fine Bruce," she said. "JARVIS, you can let Rogers go."

 _Of course, Miss Romanoff_

The elevator doors opened and Steve came out angry. "Natasha, what the hell was that for! You put the team and the city in danger!"

Bruce looked at her and his eyebrows scrunched together. "Natasha, what's Steve talking about?"

She shot an evil glare towards Steve. "I didn't want to wait until it needed to work. I had to try."

Bruce raised his hand to the burned and raw skin on his arm where the bullet grazed him. "You," he whispered.

Steve stepped closer in between the two. "Let's talk about this later. After you both have had time to calm down."

Natasha pulled her gun out and shot the wall behind Steve, the bully's barely missing his hair. "Rogers, I don't need you trying to be Captain right now. I can handle this."

He crossed his arms. "Romanoff, you ignored a direct order from me earlier and you could have put others in harm's way without any regard for them."

Natasha got up into his face and poked him in the chest. "Listen here, Rogers-"

"Both of you stop," yelled Bruce.

Natasha looked over at the scientist and saw a faint shade of green gleam in his eyes; his fingers began to twitch and a vein popped in his neck. She tensed up. "Steve, can you trust me?"

He looked over at Bruce and then back at Natasha. "Promise not to do anything stupid?"

She edged closer to Bruce who was bent over on the floor and turning a faint shade of green. "Nope."  
He nodded. "Okay then."

"Stand guard by the lab door make sure he doesn't get out," said Natasha as she sat down in front of him. She leaned down until she was face to face with him.

"Natasha-no. Get. Back," choked out Bruce. She could see that he was visibly trying to hold himself back.

"Hey," she grabbed his chin and forced him to look at her. She could see the concern and despair in his eyes. "The sun is setting soon."

He grabbed her arm and tried to gurgle out choked back words. She ran her hand down his arm until she reached his hand and she laced her fingers in his. His labored breathing became calmer and the green began to recede from his face. "Na-tash-a."

"Yeah, Bruce, it's me."

He fell against her shoulder and she let go of the breath she was holding. He sat back and looked at her with weary eyes. "It worked."

"Yeah," she whispered, "it did."

"Promise me you'll never do that again."

She looked around at the shattered glass, ruined technology and the haggard man in front of her. "Promise."

Steve walked back into the lab. "Natasha-"

"I don't want to hear it Steve."

"No, good job."

"Thanks."

Steve looked at the two and then cleared his throat. "I'll, uh, go see if Stark noticed anything." He re-entered the elevator and left the two in the rubble.

Natasha looked at her surroundings. "Stark is going to be so pissed when he finds out."

Bruce shrugged. "Well, I guess I've always been a liability."

"Don't say that about yourself."

"It's okay; I've learned to accept it." He stood up and brushed dust off of himself. "I-I've got go, you know," he gestured to his tattered clothes, "clean up."

Natasha nodded. "Of course." She watched as he walked away, knowing that something changed in their relationship.


	2. Bonus: Hitting the Grace Notes

**A/N: So it was pointed out to me in the comments that I didn't quite get the phrasing right for the lullaby. And I was like "you know what, they probably changed it a few times to get the right saying down. I can make another part to that." So because of** untapdtreasure **, you all now get a second part. Thanks for the inspiration behind it!**

 **Guest Review:**

 **Brutasha shipper: even though I didn't plan for one more chapter, aren't you glad I did?**

Hitting the Grace Notes

When Natasha's day started with a parachute drop onto the roof of a HYDRA base she didn't bat an eyelash. Taking care of the few guards that were trying to pack up and leave was protocol. Surfing through her emails on her phone while she waited for information to be downloaded to an external hard drive was a nasty habit she had picked up on solo missions, and yes, she was trying to break it. However, what did make her do a double take was when she was about to reach her temporary bedroom at Avengers tower, even thinking about visiting Clint, the Hulk came crashing through the drywall. Tony flew right through in his suit and punched the Hulk in the face, pummeling him into the floor. His punches became harder and with a groan the floor broke through and they both went down.

Natasha turned her com back on and dropped down through the ceiling of the lower floor. She landed gracefully without a sound and followed the large holes in the walls to figure out where the other two had gone. "Stark, what's wrong? What triggered Banner?"

"We were in the R&D department when one of the drones I've been developing malfunction and caught Banner by surprise. Literally. They crashed right through the window. When I looked over I was met with the green rage monster and I've been trying to keep him contained ever since."

Natasha heard Hulk roar and made a sharp right and almost ran into him. She ducked back around the corner and pulled her gun from its holster. "Stark, how is this contained," she whispered.

"Well until you showed up he was on the same floor."

"Stop and let my try the lullaby."

There was a pause.

"All right little Red. Give it a whack."

Natasha looked back around the corner and saw that Tony had backed off. "Hey," she said, but softly.

The Hulk turned around breathing heavy; she could feel his warm breath on her face. He was staring at her with a deep frown on her face.

"The sun's setting soon," she held out her hand, but Hulk just slapped her away through a wall. She spat plaster out of her mouth, shook some dust from her hair and then was right back up on her feet. She edged closer to him, backing away every so often so she didn't scare him. She raised her hands up tentatively and looked him in the eye. "The sun's setting soon."

Hulk looked at her and Natasha tip toed a little closer so she could place her hand on his even though he didn't have one outstretched. He grabbed her by the neck and instantly Natasha began to have trouble breathing.

"Hey, Oscar, stop being so grouchy and give us Banner back," shouted Tony and he blasted Hulk in the shoulder.

He looked over at Tony and dropped Natasha on the floor. He grabbed Tony by the leg and flung him out the window breaking glass.

Natasha sat up and held her hand up towards him. "The sun's setting soon."

He lumbered towards her, not stopping.

She looked in his eyes and repeated, "the sun's setting soon."

He roared and threw a desk at her. She tucked and rolled out of the way and was on the other side of the room. "Damn it. Why isn't it working?

She stepped up on a desk and vaulted into an opening in the ceiling, trying to buy herself some time. The ceiling quaked with each step the Hulk took closer to where Natasha was. "Stark, where are you?"

"Plummeting. He knocked out one of my thrusters _. Shit!_ Nat, you're on your own."

She looked down through the hole and saw the Hulk looking around for her, almost as if he was confused. Natasha took a deep breath to calm herself before dropping out of the ceiling with a soft thud.

Hulk turned around and stepped closer to her.

"Hey."

He stopped and stared at her.

"The sun's getting real low."

His frown deepened and he cocked his head to the side. He picked Natasha up and looked at her. With a confused frown he slowly raised his other hand up to her.

Never breaking eye contact, she raised her hand and placed it up against hers. She let her fingers linger on his palm before lifting them up and lightly placing them on his forearm. She left them there for moment, keeping eye contact, before moving down lower on her arm. Hulk stared at her moments, his face squinted in a look of remembrance. Natasha continued down until she reached his palm and she let her fingers linger against his calloused green skin.

Hulk looked into her eyes and they widen as he stumbled backwards. He dropped Natasha as he put his hands up to his head in disbelief. She landed on her hands and knees and she watched as he tripped backwards on a long lab table and the green began to fade from his skin. With the sickening sound of crunching bones, the Hulk was slowly turning back to Bruce.

"Is Banner back," asked Tony.

Natasha had forgotten that Tony was still on the coms and had previously been plummeting to his death. "Yeah, he's getting there. Where are you?"

"I landed fine. I'm coming up the elevator."

Natasha cautiously approached Bruce. He was covered in sheet rock dust and wearing his tattered trousers, indicating he was not expecting this. "Bruce?"

His eyes fluttered open and he took one wild eye look at Natasha before jumping up and running away. She watched as he ran down the corridor towards another set of elevator doors. She looked back at the rubble where he had been to the empty corridor where he fled.

The elevator doors pinged and opened depositing Tony. "Where is he?"

Natasha sighed. "He ran."

Tony leaned up against the elevator doorway. "Shit. I didn't mean to set him off like that. It was just an accident."

She looked at the razed room as she tucked a piece of her hair back. "Yeah, I know."

-o-O-o-

The beautiful soprano voice rising over the one hundred plus orchestra was her confirmation that Bruce was indeed in his room. Natasha pushed in on the door and saw Bruce sitting on his bed. He was leaning against the wall, eyes casted up at the ceiling, blanket wrapped around his shoulders, headphones on and leaking music out, and he was squeezing a Stark Industries stress ball in one hand. "Hello."

He didn't respond, mostly like due to the loud volume. Natasha crept closer and sat down on his bed, the appropriate amount of space between them.

He noticed the shifting weight on the bed and looked over, startled. He pulled his headphones off and Natasha could hear the soprano's aria much clearer and louder. "Natasha? What are you doing here?"

She held out the warm mug she had carried up with her. "I brought you some tea."

"Uh, thanks." He let the stress ball fall from his grip so he could accept the mug with both hands and it rolled of the bed and bounced along the floor.

She watched it roll into the open closet door out of sight. "Why did Stark even have those made anyway?"  
Bruce shrugged. "High paying C.E.O.'s get stressed. He thought it was funny?"

"Tony would think it was a joke," replied Natasha. A lull fell between the two's conversation. She filled it by gently swaying her feet from her perch on top of the bed. Bruce filled it by sipping on his tea. Bruce's music swelled and the soprano belted out an ear piercing note. "That singer has a pair of lungs."

Bruce smiled. "Yeah, in the original piece that note is two steps lower. What she sang was the grace note. It's sorta like an optional note to add to the piece. It's normally more difficult than what the original note is." He looked over at her and met her eyes. "Natasha, I don't know what happened there. I...I don't know why it didn't work the first few times and it scared me."

She placed a hand over his. "It's all right. Maybe all we needed to change was the wording. Everything's fine now."

"Except for those two R&D floors."

"Stark has money to spare."

Bruce looked down at their hands. "Natasha...I-"

 _Master Stark would like the two of you to come to the common floor as Miss Potts has returned from her business trip and he is requesting you "chill" with them and the other Avengers in the tower._

Natasha looked down at their hands and pulled hers away. "We better get to going down there."

"Yeah. Natasha?"

"Yes?"

"Thank you."

She smiled at him. "You're welcome." She walked out the door and she felt his fingers brush hers as he passed her. She looked up and saw the faintest smile on his face and it was hard for her to not smile back. 


End file.
